linux.git/fs/proc/internal.h, branch v4.17

proc: use slower rb_first()

2018-04-11T17:28:34+00:00

In a typical for /proc "open+read+close" usecase, dentry is looked up
successfully on open only to be killed in dput() on close.  In fact
dentries which aren't /proc/*/...  and /proc/sys/* were almost NEVER
CACHED.  Simple printk in proc_lookup_de() shows that.

Now that ->delete hook intelligently picks which dentries should live in
dcache and which should not, rbtree caching is not necessary as dcache
does it job, at last!

As a side effect, struct proc_dir_entry shrinks by one pointer which can
go into inline name.

Link: http://lkml.kernel.org/r/20180314231032.GA15854@avx2
Signed-off-by: Alexey Dobriyan 
Acked-by: Davidlohr Bueso 
Cc: Peter Zijlstra 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: switch struct proc_dir_entry::count to refcount

2018-04-11T17:28:34+00:00

->count is honest reference count unlike ->in_use.

Link: http://lkml.kernel.org/r/20180313174550.GA4332@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: move "struct proc_dir_entry" into kmem cache

2018-04-11T17:28:34+00:00

"struct proc_dir_entry" is variable sized because of 0-length trailing
array for name, however, because of SLAB padding allocations it is
possible to make "struct proc_dir_entry" fixed sized and allocate same
amount of memory.

It buys fine-grained debugging with poisoning and usercopy protection
which is not possible with kmalloc-* caches.

Currently, on 32-bit 91+ byte allocations go into kmalloc-128 and on
64-bit 147+ byte allocations go to kmalloc-192 anyway.

Additional memory is allocated only for 38/46+ byte long names which are
rare or may not even exist in the wild.

Link: http://lkml.kernel.org/r/20180223205504.GA17139@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: move "struct pde_opener" to kmem cache

2018-04-11T17:28:33+00:00

"struct pde_opener" is fixed size and we can have more granular approach
to debugging.

For those who don't know, per cache SLUB poisoning and red zoning don't
work if there is at least one object allocated which is hopeless in case
of kmalloc-64 but not in case of standalone cache.  Although systemd
opens 2 files from the get go, so it is hopeless after all.

Link: http://lkml.kernel.org/r/20180214082306.GB17157@avx2
Signed-off-by: Alexey Dobriyan 
Cc: Al Viro 
Cc: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: randomize "struct pde_opener"

2018-04-11T17:28:33+00:00

The more the merrier.

Link: http://lkml.kernel.org/r/20180214081935.GA17157@avx2
Signed-off-by: Alexey Dobriyan 
Cc: Al Viro 
Cc: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: rearrange args

2018-02-07T02:32:43+00:00

Rearrange args for smaller code.

lookup revolves around memcmp() which gets len 3rd arg, so propagate
length as 3rd arg.

readdir and lookup add additional arg to VFS ->readdir and ->lookup, so
better add it to the end.

Space savings on x86_64:

	add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-18 (-18)
	Function                                     old     new   delta
	proc_readdir                                  22      13      -9
	proc_lookup                                   18       9      -9

proc_match() is smaller if not inlined, I promise!

Link: http://lkml.kernel.org/r/20180104175958.GB5204@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/internal.h: fix up comment

2018-02-07T02:32:43+00:00

Document what ->pde_unload_lock actually does.

Link: http://lkml.kernel.org/r/20180103185120.GB31849@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/internal.h: rearrange struct proc_dir_entry

2018-02-07T02:32:43+00:00

struct proc_dir_entry became bit messy over years:

* move 16-bit ->mode_t before namelen to get rid of padding
* make ->in_use first field: it seems to be most used resulting in
  smaller code on x86_64 (defconfig):

	add/remove: 0/0 grow/shrink: 7/13 up/down: 24/-67 (-43)
	Function                                     old     new   delta
	proc_readdir_de                              451     455      +4
	proc_get_inode                               282     286      +4
	pde_put                                       65      69      +4
	remove_proc_subtree                          294     297      +3
	remove_proc_entry                            297     300      +3
	proc_register                                295     298      +3
	proc_notify_change                            94      97      +3
	unuse_pde                                     27      26      -1
	proc_reg_write                                89      85      -4
	proc_reg_unlocked_ioctl                       85      81      -4
	proc_reg_read                                 89      85      -4
	proc_reg_llseek                               87      83      -4
	proc_reg_get_unmapped_area                   123     119      -4
	proc_entry_rundown                           139     135      -4
	proc_reg_poll                                 91      85      -6
	proc_reg_mmap                                 79      73      -6
	proc_get_link                                 55      49      -6
	proc_reg_release                             108     101      -7
	proc_reg_open                                298     291      -7
	close_pdeo                                   228     218     -10

* move writeable fields together to a first cacheline (on x86_64),
  those include
	* ->in_use: reference count, taken every open/read/write/close etc
	* ->count: reference count, taken at readdir on every entry
	* ->pde_openers: tracks (nearly) every open, dirtied
	* ->pde_unload_lock: spinlock protecting ->pde_openers
	* ->proc_iops, ->proc_fops, ->data: writeonce fields,
	  used right together with previous group.

* other rarely written fields go into 1st/2nd and 2nd/3rd cacheline on
  32-bit and 64-bit respectively.

Additionally on 32-bit, ->subdir, ->subdir_node, ->namelen, ->name go
fully into 2nd cacheline, separated from writeable fields.  They are all
used during lookup.

Link: http://lkml.kernel.org/r/20171220215914.GA7877@avx2
Signed-off-by: Alexey Dobriyan 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-11-23T06:20:02+00:00

Pull mode_t whack-a-mole from Al Viro:
 "For all internal uses we want umode_t, which is arch-independent;
  mode_t (or __kernel_mode_t, for that matter) is wrong outside of
  userland ABI.

  Unfortunately, that crap keeps coming back and needs to be put down
  from time to time..."

* 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  mode_t whack-a-mole: task_dump_owner()

proc: : uninline name_to_int()

2017-11-18T00:10:00+00:00

Save ~360 bytes.

	add/remove: 1/0 grow/shrink: 0/4 up/down: 104/-463 (-359)
	function                                     old     new   delta
	name_to_int                                    -     104    +104
	proc_pid_lookup                              217     126     -91
	proc_lookupfd_common                         212     121     -91
	proc_task_lookup                             289     194     -95
	__proc_create                                588     402    -186

Link: http://lkml.kernel.org/r/20170912194850.GA17730@avx2
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds